Mannich bases of tetracycline compounds and amino acids



3,42,716 Patented July 3, 1962 tates XA OH D 3,042,716 MANNICH BASES F TETRACYCLHQE COMPOUNDS AND AMINO AClDS 0H Robert K. Blackwood, Gales Ferry, and Karl .l. Brunings,

New London, Conn., assignors to Chas. Pfizer 8: C0., CONHCH2R Inc, New York, N.Y., a corporation of Delaware H H No Drawing. Filed Dec. 4, 1961, Ser. No. 156,950 on 0 0H 0 5 Claims. (Cl. 260-519)' A B D The present application is concerned with a new group of substituted-tetracycline antibiotics, the acid and base salts thereof and with the process for their preparation.

The present substances are derivatives of tetracycline antibiotics with formaldehyde and an amino acid. These new ll substances are prepared from tetracycline antibiotics by OH O OH 0 a novel synthetic process and are particularly adapted for and the acid and base salts thereof, wherein A is selected therapeutic use by virtue of improved physiological and from the group consisting of H and CH B 'is selected pharmaceutical properties. from the group consisting of H and OH, D is selected The tetracycline antibiotics comprise a group of biofrom the group consisting of H and N(CH X is selected logically active perhydronaphthacene derivatives having from the group consisting of Cl and Br, and R together the following essential structural features. The numberwith the associated amino group constitutes the mono- 7 ing system indicated is that employed by Chemical Ab- Valent radical of an amino acid selected from the group t t f I consisting of w-aminoalkanoic and a,w-diaminoalkanoic acids of from three to six carbon atoms. In the case of a,w-diaminoalkanoic acids the bonding is through the nitrogen. The present new compounds are amphoteric and thus form salts with both acids and bases.

These novel substances have a number of unique physiological and pharmaceutical properties not shared by the parent antibiotics and derivatives thereof. The subject compounds have a higher water solubility than the corre- Amoflg the biologically active members of this l are spending parent antibiotics and the further advantage that those Containing the following Substitueflt gr 0111381 their acid salts do not rapidly hydrolyze and precipitate in aqueous media on standing or on adjusting pH over a range of from 3 to 8. Further, the present new comsubstituents Common Name pounds appear to be rapidly and completely absorbed a from the gastrointestinal tract. They provide to animals H, H, -QH ,1 a.on tetracycline, the protection against various types of infections either arse;:rsaraaaaaas experimentallyenmllywmced- Theinstam r-N chansons-01131221011 fi-deoxy-fi-oxytetracyclme. pounds are particularly well adapted for parenteral admin- *"iiiiffiffSQQfifi istration providing longer serum levels than the corre- 4-N(CH ,6 OHg,l2a-OH fi-deoxyte tracycline. spending parent antibiotic when administered intramus- 4'N(OH3)112a'OH gggfg ggj fl f cularly. Their improved water solubility over a wide 4-N(CH3)z,6OH,6-CH3,7-Br,l2a-OH -r 7-brombtetraeycline. pH range makes them superior to the parent antibiotics lgfi gg 'gg 40 for intravenous administration of the antibiotic. The acid 6-OH,eCHQ,12a-OH- l-desdimethyla addition salts of the present new compounds are more tomcH aoa rt tgthftiifs mq r p w g c1 ortetra y suc as ower a ano s propy ene g yco g ycero an e *N fi'dememyltemcychne' like than are the free base forms. This adapts them for use in various sterilized pharmaceutical preparations. The acid addition salts are particularly well absorbed The Compounds- Of the P invention are derivatives from the gastrointestinal tract and provide satisfactory of tetracycline antibiotics as described above, formed by tibiotic bl od levels on either oral or parenteral adreaction with formaldehyde and an amino acid which 5 ministration. Animals are protected from infection by contains an amino group at the w-position, i.e. on the organisms sensitive to the antibiotic invitro. carbon atom furthest removed from the carboxyl group. As previously mentioned, the present new compounds Although other such amino acids are contemplated by the are substances formed by the reaction of the parent antipresent invention, of particular value are w-amino-alkanoic biotic W formaldehyde and an amino acid- The Teacand a,w-diaminoalkanoic acids containing from 3 to 6 cartionfis t d y m y contacting the Selected t abon atoms, f example, fi a1a nin@ and lysine pcycline antibiotic with formaldehyde and the amino acld aminocaproic acid). The present new compounds are in an Q f medmm Whlch may be f as deslfed represented by the following formulae; 'by the addition of water soluble organic solvents to 1mprove the solubility of the various reagents. For example, the tetracycline antibiotic when employed in the anhy- E 3 D drous free base form is preferably dissolved in a watermiscible solvent e.g. isopropyl alcohol, dioxane, tetra- OH hydrofuran, lower alkyl ethers of ethylene glycol and OH diethylene glycol such as the dimethyl ether, dimethyl -CONHCH2R formamide and the like. It is preferred to employ sufli- II [I cient solvent to maintain the antibiotic in solution when 0H 0 OH 0 added to the aqueous reaction medium. The reagents may be added simultaneously or individually, in any order. It is generally preferred to. add the tetracycline antibiotic best results are thus obtained. Efiicient mechanical mixing of the reaction medium, while not essential, is found particularly helpful, especially during the addition of the tetracycline antibiotic. I

The reagents are preferably employed, in a substantially equimolar ratio. Although excesses of the formaldehyde and selected amino acid may be employed, no substantial s to those skilled in the art.

The valuable products of the instant invention are cathe presence of amino groups and a carboxyl group. For example, lysinomethyltetracycline is capable of forming a mono-, dior trihydrochloride due to the presence of 3 amino groups. Further, due to the presence of the free carboxyl group, the instant compounds'may form a variety of salts with either inorganic or organic bases. Exemplary of these salts are alkali metal salts, such as sodium and potassium salts, the ammonium salt and alkaline earth metal salts, such as the calcium salt, as Well assalts with organic amines. Such salts of course are prepared by conventional procedures recognized by those skilled in the art.

The'various forms of the tetracycline antibiotic may beemployed in the instant process, for example, acid addition salts as well as. the. free base in either hydrated or anhydrous form. The amino acid employed in the present Other proceto a mixture of formaldehyde and the amino acid since 4 EXAMPLE I Amido-N- (Lysinomethyl) Tetracycline Hydrochloride To 18.3 g. of L-lysine hydrochloride dissolved in 100 ml. of water is added of 37% aqueous solution of formaldehyde. To the resultant mixture is added 44 g. of anhydrous tetracycline dissolved in 500 ml. of tetrahydrofuran. After thorough mixing the product forms over a period of about minutes as an oily layer which after separation from the aqueous phase isadded dropwise to 3 liters of stirred isopropyl alcohol. The product after recovery by filtration, is reslurried with acetone, filtered and dried at 65 C. at reduced pressure.

The product thus obtained has a bioassay of 500 mcg./ mg. (K. pneumoniae oxytetracyoline assay), ultraviolet assay, 46.5% as tetracycline hydrochloride, shows an ultraviolet absorption spectrum in acidified methanol almost identical in shape to that of tetracycline, and shows when spotted as an aqueous solutionan Rf value of 0 pable of forming salts with either acids or bases due to with a tendency to form a streak out 'to the same Rf as tetracycline in paper chromatographic system employing the following solvent system: '20: 10:3 nitromethanezchloroform:pyridine.

7 EXAMPLE II Amido-N-(Lysinomethyl) Orytetracycline Hydrochloride The procedure of Examplel is repeated employing oxytetracycline in place of tetracycline to. obtain the corresponding product. V

The product has a bioassay of 460-465 meg/mg. (K. pneumoniae' oxytetracycline assay) ultraviolet assay,

' 48.5% as tetracycline hydrochloride, shows ultraviolet spectrum in acidified methanol almost identical with that process may be utilized as the acid addition salts or as the free amino acid. If a salt of either the tetracycline or amino acid is used, it is generally preferred to employ mineral acid salts, exemplified by the hydrochloric acid salts, since these are readily available and give excellent results. nitric, hydrobromic and the like, in addition to hydrochloric acid salts. As is recognized by those skilled in the art, the product obtained will correspond with the utilized in one of its optically active forms, for example,

D' or L-lysine, as the racemic compound, DL-ly-sine, or as a mixture of the optically activefonns. It is generally preferred to employ L-lysine since the L-amino acidis the biologically active form. The pro duct resulting therefrom' maybe found more advantageous for use -in the animal body. Of course, the product obtained with'the other forms of lysine possess the valuable properties as heretofore described. i

The antibiotic in vitro spectrum of the present new compounds corresponds with that of 'the parent antibiotics from which they are derived. The effectiveness of the tetracycline antibiotics is well-documentedin the medical literature. r The following examples are given by way of illustration and are not to beconstrued as limitations of this invention many variations of which are possible without 7 departing from the scope and spirit thereof.

These,'of course, include phosphoric, sulfuric,

of oxytetracycline and when spotted as an aqueous solution, shows a streak out to the-same Rf exhibited by tetracycline in the same solvent system as employed in Example I.

EXAMPLE HI Amido-N- S-A laninomethyl Tetracycline To a stirred flask, the following reagents are added in order: 7

This application in part discloses and claims subject matter disclosed in our copending applicationSerial No.

814,396, filed May 20, 1959, now abandoned.

Precipitation of a gummy solid begins-almost immediately after stirring and continues for almost 5 minutes.

The gum is separated from the mixture, placed in 500 ml.

of ethylene glycol dimethylether and stirred until a filterable product results. The product is then obtained by filtration followed by ether washing. I

The product thus obtained has a bioassay of 650 mcg./ mg. (K. pneumbniae oxytetracyc'line assay), ultraviolet assay, 69% as tetracycline hydrochloride, shows an ultraviolet spectrum in acid methanol'almost identical in shape to that of tetracycline'and when spotted as an aqueous solution shows an Rf value of 0 with a tendency to form a streak out to the same Rf as tetracycline in a paper chromatographic system as described in Example I.

EXAMPLE Iv In a similar manner the product of Example 111 is converted to the desired hydrochloride salt. Other acid-addition salts of the 'valuable products of this invention are prepared by the above procedures by substituting for hydrochlon'c acid, the following: hydrobromic acid, phosphoric acid, sulfuric acid, acetic acid, tartaric acid, malic acid, citric acid, gluconic acid and the like.

EXAMPLE V The free "base corresponding to the product of Example I is dissolved in an aqueous solution containing an equivalent of sodium hydroxide. The resultant solution is frozen and dried under reduced pressure to obtain the sodium salt as a powder.

Similarly, the potassium, calcium and magnesium salts are obtained.

The salts of the present new compounds with pharmaceutically-acceptable acids and bases are particularly valuable for the preparation of various dosage forms. Those Wtih pharmaceutically-unacceptable acids and bases are useful for the purification of the present compounds and also for the preparation of pharmaceuticallyacceptable salts.

EXAMPLE VI The procedure of Example I is repeated employing, in place of lysine, the following amino acids:

'y-Aminobutyric acid u,A-diaminovaleric acid Arginine A-aminocaproic acid Similar results are obtained.

EXAMPLE VII The procedure of Example I is repeated employing, in lieu of tetracycline, corresponding tetracyclines to obtain the following products:

Amido-N- lysinomethyl) chlortetracycline Amide-l (lysinomethyl) -6-deoxy-5-oxytetracycline Amido-N- (lysinomethyl) -4-desdimethylamino-5- oxytetracycline Amido-N-(fi-alaninomethyl) -6deoxytetracycline Arnido-N- (lysinomethyl) -6-deoxy-6-demethyltetracycline AmidoN- (lysinomethyl) -7-bromotetracycline Amido-N- (lysinomethyl) -6-demethy1-7 -chlort etracycline Amido-N- B-alam'nornethyl) -4-des dimethylaminotetracycline Amido-N- (lysinomethyl) -4-desdimethylamino-7- chlortetracycline Amido-N- (lysinomethyl) '-6-demethyltetracycline 6 What is claimed is: 1. A compound selected from the g oup consisting of CH: B OH D OH OH] CONHCHzNHR OH O OH --OONHOH:NHR

and the acid-addition and base salts thereof,

wherein A is selected from the group consisting of hydrogen No references cited.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,042,716 July 3, 1962 Robert K. Blackwood et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, lines 65 to 70, for the two-position substituent "C0NHCH R" read CONHCH NHR column 2, lines 1 to 15,

for the two-position substituents of each structural formula,

for "CONHCH R" read -CONHCH NHR column 6, lines 18 to 24, for the 11-position substituent "H" read 0 Signed and sealed this 11th day of September 1962.

(SEAL) meat:

ERNEST w. SWIDER DAVID LADD testing Officer Commissioner of Patents 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF
 3. AMIDO-N-(LYSINOMETHYL) TETRACYCLINE. 